It may be used for coats of many colours (5)
I believe the answer is:
paint
'coats of many colours' is the definition.
The answer and definition can be both man-made objects as well as being singular nouns.
Maybe they are linked in a way I don't understand?
'it may be' is the wordplay.
I cannot really see how this works, but
'it' could be 't' (abbreviation. e.g. in 'tis) and 't' is found within the answer.
The remaining letters 'pain' is a valid word which might be clued in a way I don't see.
This may be the basis of the clue (or it may be nonsense).
'used for' is the link.
Can you help me to learn more?
(Other definitions for paint that I've seen before include "Daub" , "Coloured liquid in tins" , "Item used by 23 Across" , "Surface coating or decoration" , "Artist's material" .)